In the past, the mainstay of the sod industry has been Kentucky Bluegrass. Its greatest advantage from a sod grower's point of view is its rhizoming characteristic. ln other words, it produces shallow underground shoots that upon surfacing produce another new plant. Rhizoming results in continuous lateral expansion from a "mother" plant to the point of eventually creating a very dense turf consisting of mother plants and their surrounding offspring.
Because of the foregoing characteristic and a desire to save seed costs, existing seeder devices were not designed to maximize plant density.
Relatively recently, completely different strains of grasses have been developed which have better water conserving and disease-resisting characteristics than Kentucky Bluegrass. These new kinds of grasses are known as improved perennial ryegrass and improved turf type tall fescue. Both the perennial rye and tall fescue do not produce rhizomes. The density of their turf is completely dependent upon original seed rate: that is, density, and uniformity of seed distribution: that is, spacing between longitudinal seed beds or troughs. In order to produce the best appearing sod possible, both factors are critical.
Seed rates are generally determined by each sod grower's individual parameters; for example, cost of seed, germination percentage, etc. Uniform seed distribution, in turn, is limited by the type of seeding device and the particular method of seeding. At the present time, the majority of sod growers use the Brillion "Turf Maker" seeder now available on the market. With this mechanism, seeds are planted in rows approximately two inches apart. If perennial rye or turf type tall fesque strains of grasses are to be grown, the resulting rows of plants do not grow together beyond their two inch spacing. The gap rather is filled by horizontal leaf growth, greatly detracting from the overall turf appearance.